Allocation and transfer of photosynthetic 13 C in the vegetation‐soil system and its response to permafrost degradation

• Published in: Land Degradation & Development
• Main Authors: Che, Lina, Xuan, Liqiang, Wan, Luhe
• Other Authors: National Natural Science Foundation of China
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Active layer thickness; permafrost
• Online Access: http://dx.doi.org/10.1002/ldr.4471; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ldr.4471; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/ldr.4471

Abstract The Xing'an Mountains, located on the southern edge of the Eurasian permafrost zone, are sensitive to permafrost degradation. In particular, the impact of wetland degradation in permafrost regions on carbon sequestration capacity cannot be ignored. Therefore, there is an urgent need to understand the allocation and transfer of photosynthetic 13 C in the wetland vegetation‐soil system and its response to permafrost degradation. Three regions with different types of permafrost were selected predominantly continuous and island permafrost (located in Mohe); sparse island permafrost (located in Heihe); and isolated patches of permafrost (located in Yichun). The effects of permafrost degradation on the allocation and transfer of photosynthetic 13 C in trees, shrubs, herb vegetation, and mosses were investigated using isotope tracing techniques, redundancy analysis, and structural equation modeling. Mohe had the largest 13 C excess and more transfer of shrubs and herbs to the underground carbon pool. The recoveries of photosynthate‐ 13 C for Larix gemlini , Vaccinium uliginosum , and Sphagnum sp. were significantly different in different permafrost regions using Tukey's honestly significant difference (HSD) post hoc comparisons of means tests. The amount of Δphotosynthate‐ 13 C transfer was larger in Mohe than in Heihe and Yichun. The allocation of photosynthetic 13 C in the plant roots in the three permafrost regions was positively correlated with the total soil phosphorus content. The active layer thickness was an important factor affecting the transfer of Δphotosynthate‐ 13 C. The allocation and transfer of photosynthetic 13 C to the subsurface were larger in the predominantly continuous and island permafrost areas than in the sparse island and isolated patch permafrost regions. The allocation and transfer of photosynthetic 13 C in the vegetation‐soil system were affected by the soils' physicochemical properties and the environmental changes after permafrost degradation.